why do you need to do anything with wan ip?assuming your cpe is currently working just connect it to router wan port using lan & try surfing net on pc.you don't even have to configure router,just connect it & see if it works.if it does then no problem but if it doesn't then post result of ipconfig /all.make sure that net is working from pc directly connected to cpe & only after that connect the router between between cpe & pc.